Tachometer Calibration
Due to the exceptionally high stresses that may be generated by particular propeller/engine combinations at certain engine RPM, many propeller and aircraft manufacturers have established areas of RPM restrictions and other restrictions on maximum RPM for some models. Since there is no post-manufacture accuracy requirements for engine tachometers, tach inaccuracy could lead to propeller failure, excessive vibration, or unscheduled maintenance. H&S Propeller strongly recommends having your tachometer calibrated or overhauled in conjunction with your engine overhaul time. We have experienced many problems due to inaccurate tachometers.
If your aircraft is high performance or turbo-charged this is especially true, as your engine performance data needs to be accurate.
There are many inexpensive battery operated tachometer “checkers”, which are pointed at running propeller, and tachometer indications can be compared to test equipment reading. This is the quickest method for verifying tachometer indications.